99 crownvic won't idle

I have a 99 crownvic and it won't idle only during humid days >50% relative humidity or above. During cool days it idles fine. I wonder if it's my oxygen sensors going out.

Thank you for any suggestions.

Have it checked for trouble codes. If it were the O2 sensor your computer would run in open loop but the idle wouldn't change.

What happens if you depress the accelerator *slightly*? If it will continue running, the most likely culprit is the Idle Air Control solenoid. Simple 15 minute repair, and the part is not too expensive either.

If that is the problem, and you replace it, please do yourself a favor and get an OE valve (Ford or Motorcraft), they really are better quality than the aftermarket parts.

Yes sir, it will continue running. I am driving with 2 feet. Great, I'll change out the Idle Air Control solenoid. I bought this Service Information CD from Ford so I can find out exactly where it is. Really appreciate your help.

Glad to help, and I hope that fixes it for good!